incident vs. reflective metering

[Michael Geschlecht]

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Hello Pico,

 

That is actually quite interesting.

 

Since the "Bulb" circuit in earler "M" cameras is a separate circuit, as is the hot shoe on an M5: Does that mean that the "Blitz" circuit on the back of the "M" or/& the "hot shoe" on the top of current & earlier models can also be used with bulbs & a flash meter if a person uses a cord?

 

Best Regards,

 

Michael

[jmr237]

Thank you everyone for the thoughts and input. I still am a bit fuzzy on why an incident meter will place everything in the correct zone, but I'll figure it out.

 

Since my initial post, I bought the Lumu incident light meter. It's a small white dome that plugs into an iPhone's headphone jack. I removed the batteries from my M6 and shot a roll just using the readings from the Lumu. It was much less cumbersome than I thought it would be. In fact, I was pleasantly surprised to find that it offered usability improvements over an in-camera meter. For example, instead of wondering what to meter or whether to deviate from the camera's suggested metering, all I had to do was meter my subject, set the camera, and shoot. The app is very good an allows for filter correction, stop interval preference (1/3, 1/2, etc), continuous reading, and so on.

 

I also found that this method help me develop a stronger mental connection between the light and the aperture and shutter speed settings. I think this is because I was looking at the readings on the meter, and seeing the actual values, rather than chasing the little red arrows within the finder. I also found it instructive to move the Lumu throughout a scene and observe how the light changes translated into EV values.

 

I suppose this is not news to those of you who have used hand-held meters. But it is the first time I've tried that approach, and I found that it worked very well. I'm looking forward to getting the scans back from the lab later this week.

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[giordano]

I still am a bit fuzzy on why an incident meter will place everything in the correct zone, but I'll figure it out.

 

 

 

It's a category error to think of an incident light meter as "placing things in zones" because as I said before they are quite different approaches to the exposure problem. Moreover the Zone system was developed specifically for exposing and developing monochrome negatives for making high class prints, while incident light metering emerged from movie studios and colour reversal work.

 

 

 

If absolutely necessary you can think of an incident meter as putting the brightest non-specular highlights _which may not exist in the scene you are photographing_ into whatever is the correct zone for such things. Nothing more.

 

 

 

_In practice_ this means that mid tones are correctly exposed too, while shadow detail is left to chance, or rather the latitude of the technology or process you are using (if that's insufficient you use supplemental lighting).

 

 

 

That, in practice, is exactly what's needed, for various reasons, in almost all cinematography, video, reversal and still colour work - especially in non-digital processes where you can't adjust contrast post-exposure.

 

 

 

But for high class monochrome neg/pos work, shadow detail is far more important and post-exposure contrast adjustment is part of the process. Since incident metering pays no attention to shadows it is less suitable than an intelligent use of a reflective meter (of which the Zone system is the most highly elaborated).

 

 

 

I also found that this method help me develop a stronger mental connection between the light and the aperture and shutter speed settings. I think this is because I was looking at the readings on the meter, and seeing the actual values, rather than chasing the little red arrows within the finder. I also found it instructive to move the Lumu throughout a scene and observe how the light changes translated into EV values.

 

 

 

If you weren't already used to doing this with a reflective meter you probably don't fully understand the Zone system, making it even more of a mistake to try and think of incident metering in zone terms.

[jmr237]

If you weren't already used to doing this with a reflective meter you probably don't fully understand the Zone system, making it even more of a mistake to try and think of incident metering in zone terms.

 

I appreciate your comment, but your tone could be more respectful. You are assuming that I don't understand the zone system and that I have not tried metering a scene with a reflective meter. Of course I understand you can do this with an in-camera reflective meter. But using the Lumu provides instant readings on the EV values. The M6's meter simply goes to a left or a right arrow, rather than providing information about the relative amount of over- or under-exposure. Hence it does not facilitate a quick scan of meter values within a scene (unlike the M7 or FM3a that I used to use).

 

I don't mean to sound strident, but I think these forums are at their best when we take care to interact with each other respectfully and avoid making assumptions or leaping to conclusions about others' knowledge or motivations. A good test is to ask yourself if you would phrase something the same way if you were talking with that person face to face. If not, it's a sign that your post should be toned down.

[chrism]

I think, when we reply to a thread like this—where a user asks for advice from more experienced members— we would all be well advised to think of ourselves as teachers. Teachers, good ones, don't show off how much they know, nor do they denigrate their pupils, but they do think about the best way to impart their knowledge to others.

 

Now, to lighten the tone, just imagine Ansel Adams climbing to various points on the Half Dome to take incident readings. That illustrates nicely why we sometimes prefer reflective readings. Despite that, I have many cameras with no meter and when I use my Gossen, I always use incident readings when practicable, and your first reply in this thread from IkarusJohn explained why (it was actually an very good précis of the theory and practice of light metering in 400 words or less).

 

Chris

[giordano]

I appreciate your comment, but your tone could be more respectful. You are assuming that I don't understand the zone system and that I have not tried metering a scene with a reflective meter. Of course I understand you can do this with an in-camera reflective meter. But using the Lumu provides instant readings on the EV values. The M6's meter simply goes to a left or a right arrow, rather than providing information about the relative amount of over- or under-exposure. Hence it does not facilitate a quick scan of meter values within a scene (unlike the M7 or FM3a that I used to use).

 

 

 

 

 

I don't mean to sound strident, but I think these forums are at their best when we take care to interact with each other respectfully and avoid making assumptions or leaping to conclusions about others' knowledge or motivations. A good test is to ask yourself if you would phrase something the same way if you were talking with that person face to face. If not, it's a sign that your post should be toned down.

 

 

 

I'm sorry I upset you. I'd probably have expressed the same thought face to face, if in different words. Thinking about it, I guess it's because to me (a) the Zone system involves optimising both exposure and development of each sheet of film in order to place each important tone in the desired zone, and I find it hard to imagine doing that without an exposure calculator; and ( if you're not doing that there's no need to introduce the concept of zones at all. But that's just my opinion.

[robert_parker]

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I've just got a Lumu myself-I'm particularly interested in its unusually strong low light sensitivity that may make it useful for street scenes in the evening and night under street lamps

[250swb]

I'm sorry I upset you. I'd probably have expressed the same thought face to face, if in different words. Thinking about it, I guess it's because to me (a) the Zone system involves optimising both exposure and development of each sheet of film in order to place each important tone in the desired zone, and I find it hard to imagine doing that without an exposure calculator; and ( if you're not doing that there's no need to introduce the concept of zones at all. But that's just my opinion.

 

Just about the first thing I was taught in formal photographic education was The Zone System, so I was in at the deep end. As you know it involves tests with individual sheets of film, the developer, making step wedges, in fact calibrating the entire procedure from choice of film to the grade of paper. And the thing that I brought away from it in the long run is that it is not an elitist system, and only meant for a specialist way of working (even Ansel used it with roll film). It is true you need to understand the system to appreciate what you are doing, but knowing what exposure values will do with a film and developer you understand well is as valuable in the middle of a roll of 36 as following the entire formal procedure with sheet film.

 

Picturing in the minds eye the movement of tones relative to exposure and processing is a creative language that the reflective meter can bring to all photographers if they understand which parts of the Zone System they need, even though they may not take it to the ultimate end by tying it in with darkroom printing. Taken as a simple concept the idea of zones whether they are tied to the formal system or not allows the photographer to express the things they want the picture to be, they are engaging in the language of photography which is no bad thing, and it should not be censored by pedantry. And that's just my opinion ;-)

 

Steve

[Michael Geschlecht]

Hello JMR,

 

Very nice & properly exposed photos.

 

Another way to look at the difference between incident & reflected metering is:

 

Film is exposed by the light falling on the scene being photographed. More light = more exposure. Less light = less exposure.

 

A reflected meter is calibrated to assume that it is reading 18% of the light falling on an average reflectivity subject. This light has been reflected back from the subject to the meter.

 

Often this produces a correct exposure. Sometimes it does not. Various photographers have devised various systems for adjusting non-conforming readings in order to produce appropriate results.

 

An incident meter doesn't care whether or not the scene you are metering or photographing is 18% gray.

 

It measures the light falling on the subject. The reasoning is that it is the light falling on the subject that exposes the film & that the photgrapher wants dark things to be reproduced as dark & light things to be reproduced as light. The specific subject or/& circumstance is usually irrelevant. Altho not always.

 

Read the light falling on the subject. Set the camera/lens appropriately. Take the picture.

 

I hope this helps.

 

Best Regards,

 

Michael

[sblitz]

you can also meter the darkest thing you want to show more than pure black and then open 2 stops from there. conversely you can meter the lightest think you want to not be burnt out and close 2 stops. pretty much gets you to the same place, a well exposed photo.

[jmr237]

An incident meter doesn't care whether or not the scene you are metering or photographing is 18% gray.

 

It measures the light falling on the subject. The reasoning is that it is the light falling on the subject that exposes the film & that the photgrapher wants dark things to be reproduced as dark & light things to be reproduced as light. The specific subject or/& circumstance is usually irrelevant. Altho not always.

 

Read the light falling on the subject. Set the camera/lens appropriately. Take the picture.

 

I think I am finally getting it. My problem is that I assumed that an incident meter translates its reading into some type of tonal value, hence my question about what zone that value would fall into. Now I think I understand that the incident meter is simply measuring an absolute value of light; it does not know or care how that light is absorbed or reflected by the material it falls on (e.g. a dull back carpet vs. glistening white snow). That's why you can, as Michael points out, simply meter the light, set the camera, and shoot.

 

Today I shot two rolls while out and about. I used the Lumu incident meter for exposure settings (I still have the batteries removed from the M6). As I mentioned above, I am finding this to be an easier and more relaxed way to shoot than chasing the little arrows in the finder. Will let you all know how they turn out.

 

Thanks again for the ideas and input.

[TomB_tx]

I've used both types of meters through the years, and find that a reflected reading from a grey card gives about the same reading as an incident meter. I prefer a semi-spot reflected (like the M5) where I can pick an area appropriate to grey. A big key is learning not to obsess or over-meter, whichever type you use. Meter the scene, and use judgment to tweak the settings for each shot. Has worked great with my M4 and MR meter since 1969.

[bocaburger]

I also have used both types of meter over the years, in fact all my handheld meters do both, with a little white dome that slides on and off the cell for incident readings. I also use the in-camera meter as an incident meter by metering off my palm and adding 1 1/2 stops. Sometimes I'll point the camera at the clear blue sky away from the sun and use that as a reading. Sometimes I'll use Sunny 16 and compensate from there. Any form of metering can be fooled in certain conditions (although the multi-zone matrix/evaluative metering in Nikons and Canons SLRs is pretty darn good most of the time). The more you understand about exposure (and it's really not complicated although discussions often make it seem more so than it needs to be) the better you can interpret the meter reading and make compensations if necessary. And then there's bracketing, and with digital, some exposure leeway in post processing as long as important highlights aren't blown out.

[sblitz]

Here is another great thing about what you are doing -- you are firing the cognitive brain waves and thereby keeping that in-house organic computer working and tuned up. The value there is well beyond the quality of the picture you create.

[Michael Geschlecht]

Hello Everybody,

 

An advantage to having both an incident meter & a reflected light meter (or 1 meter that does both) is that there is no need to choose beforehand to use 1 method or the other exclusively. A person can use the 1 that best fits the individual set of circumstances currently in front of them.

 

Hello JMR,

 

After you are comfortable using your incident meter you might consider putting the batteries back in your camera.

 

Continue metering with the incident meter & setting the camera appropriately.

 

Then find an area within the framelines of the image that you are photographing which is representative of an average 18% reflective gray within that scene & is also the same size as the metering pattern for that specific lens.

 

Activate the in camera meter & measure. Both meters should indicate pretty much the same exposure.

 

If the 2 readings are not close it is possible that the 2 meters are calibrated to different standards.

 

A simple test to see if both meters are calibrated to the same standard is to find & meter an approximately 18% reflectance area with both meters. As an example: You might use an evenly lit medium dark wall of approximately 18% reflectance.

 

If both meters read apprroximately the same then the different readings of the previous scene might be due to metering technique.

 

If the 2 meters read differently in the same situation then this is an easy thing for you to adjust yourself.

 

If either of the 2 paragraphs just above is the situation: Come back here & we can talk (actually write).

 

Best Regards,

 

Michael

[MarkP]

I've just got a Lumu myself-I'm particularly interested in its unusually strong low light sensitivity that may make it useful for street scenes in the evening and night under street lamps

 

Exactly why I ordered one yesterday. The EV range of -4 to 20 is what sold me on it.

 

I don't always carry a light meter but I carry my mobile phone with me all the time as I'm always on call for work.

[IkarusJohn]

Exactly why I ordered one yesterday. The EV range of -4 to 20 is what sold me on it.

 

I don't always carry a light meter but I always carry my mobile phone with me s I 'm always on call for work.

 

+1 Mine is on the way.

[Michael Geschlecht]

Hello John,

 

Mark said -4, not +1.

 

At +1 you can do almost as well with an MR Meter since its range is +2 to +18.

 

Best Regards,

 

Michael

[IkarusJohn]

Hello John,

 

Mark said -4, not +1.

 

At +1 you can do almost as well with an MR Meter since its range is +2 to +18.

 

Best Regards,

 

Michael

 

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[robert_parker]

Hello John,

 

Mark said -4, not +1.

 

At +1 you can do almost as well with an MR Meter since its range is +2 to +18.

 

Best Regards,

 

Michael